Field of the Invention
The present invention relates to a fixing solution used in an image forming method of a wet fixing system using an electrophotography and an image forming method using this fixing solution.
Description of the Related Art
An image forming device such as a printer, a facsimile machine or a copying machine is a device that forms an image including characters and symbols on an image support such as paper, cloth or an OHP sheet based on image information.
In particular, the image forming devices of the electrophotography are widely utilized in, for example, offices or the like, because it is possible to form a high minute image on a plain paper at high speed. In the image forming device of the electrophotography described above, there is widely used a thermal fixing system in which the toner constituting a toner image on an image support is heated and melted, the molten toner is pressurized, and thus the toner image is fixed on the image support. With such a thermal fixing system, it is possible to provide a high fixing rate and a high image quality.
However, in the image forming device of the thermal fixing system described above, about half or more of consumption power is consumed to heat the toner. In contrast, from the viewpoint of measures against environmental issues in recent years, there has been desired a fixing method in which lower power consumption (energy saving) is ensured. That is, it is desirable to use a fixing method in which the temperature at which the toner is heated to be fixed is extremely lowered compared with in the past or in which heating of the toner is not necessary. In particular, a non-heating fixing system in which a toner image is fixed on an image support without a toner being heated is ideal in terms of low power consumption.
As the non-heating fixing system, a wet fixing system is known in which a fixing solution for softening a toner is supplied to a toner image to thereby fix it on an image support. However, there are a few problems in the wet fixing system.
For example, a problem exists in which, when in order for a high fixing strength to be obtained, a large amount of fixing solution is coated on an image support such as paper, the toner particles constituting a toner image are moved on the image support by the excessive amount of fixing solution to thereby degrade the image quality, and a problem exists in which drying time is elongated, which degrades the fixing responsiveness (see Patent Literatures 1 and 2). Furthermore, a problem exists in which a remarkable feeling of liquid left in paper (a wet feeling when paper is touched with a hand) is produced.
Moreover, for example, when, as a fixing solution, an oil droplet water solution-type fixing solution is used in which an organic compound insoluble or poorly soluble in water is dispersed and mixed with water, if a large amount of fixing solution is supplied, an image support such as paper absorbs water in the fixing solution, and thus a crease or a curl is generated on the image support. This causes a problem of reducing the stable and high-speed transport properties of the image support which is required in the image forming device (see Patent Literature 3).
As to the fixing responsiveness, when the rate at which the fixing solution is softened for the toner is low, it is necessary to set the image processing rate of the image forming device to low, and thus there is a problem in which an image processing capacity that the image forming device originally has cannot be achieved. In particular, when image formation using a color toner is performed, toner particles of different colors are stacked to increase the thickness, and thus it is necessary to use a fixing solution having a high softening rate with respect to the toner (see Patent Literature 4).
As described above, in the fixing solution used in the wet fixing system, faster fixing rate and faster drying rate are required to be achieved while the supply amount of fixing solution is reduced and excellent fixing performances such as reducing a wet feeling in a formed image and having a high fixing strength are required.